XIV 



MONOTOCARDI A — TAENIOGLOSS A 



419 



the sides, channelled at each end, labium inflected ; no opercu- 

 lum. Jurassic . Genera: Oinda (including Ampldperas^ 



Transovula^ Cyjjlioma^ Radius^ Simnid)^ Pedieidaria^ Cypraea 

 (with subg., Cypraeovula, Cypraedia^ and Trivici)^ and Erato. 



Fam. 39. Doliidae. — Foot expanded, wider and longer than 

 the shell, truncated and thickened in front, siphon very long and 

 narrow ; central tooth with very strong median and small lateral 



Fig. 277. — Three stages in tlie growth of Pteroceras rugosum Sowb., E. Indies, 

 showing the development of the ' fingers.' 



and basal cusps, lateral and marginals bluntly falciform ; shell 

 ventricose, without varices, spire short, outer lip generally simple, 



anterior canal rather wide, no operculum. Cretaceous . 



Genera : DoUum (subg., Malea, outer lip thickened, denticulate, 

 reflected) ; Pinda^ mantle with two lateral lobes reflected over 

 part of the shell, shell fig-shaped (Fig. 278). 



Fam. 40. Cassididae. — Foot broad, siphon long (radula. Fig. 

 125, p. 223) ; shell ventricose, with varices, spire short, outer 

 lip reflected or thickened, anterior canal short, recurved narrow ; 

 operculum semilunar, with ribs radiating from a marginal 



